Bar code symbol scanning system having a holographic laser scanning disc utilizing maximum light collection surface area thereof and having scanning facets with optimized light collection efficiency

• US 6,199,759 B1
• Filed: 09/30/1997
• Issued: 03/13/2001
• Est. Priority Date: 08/17/1994
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Amundsen, Thomas, Knowles, Carl Harry, Groot, John, Dickson, Leroy
• Primary Examiner(s): Le, Thien Minh
• Application Number:
  US08/941,781
• Time in Patent Office: 1,260 Days
• Field of Search: 235/462, 235/472, 235/469, 235/467, 235/470, 235/454, 235/456, 235/463, 359/574, 359/573, 359/563, 359/18, 359/17
• US Class Current: 235/472.01
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 26/106 having diffraction gratings as scanning elements, e.g. holographic scanners holographic optical elements G02B5/32, holography G03H
• CPC Class Codes: G06K 17/0022 arrangements or provisious for transferring data to distant stations, e.g. from a sensing device "transfer between computer elements G06F13/00 "; data-transmission H04L
• CPC Class Codes: G06K 2207/1012 Special detection of object
• CPC Class Codes: G06K 2207/1013 Multi-focal
• CPC Class Codes: G06K 2207/1016 Motor control or optical moving unit control
• CPC Class Codes: G06K 2207/1017 Programmable
• CPC Class Codes: G06K 2207/1018 Source control
• CPC Class Codes: G06K 7/10 by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
• CPC Class Codes: G06K 7/10564 Light sources
• CPC Class Codes: G06K 7/10584 Source control
• CPC Class Codes: G06K 7/10594 Beam path
• CPC Class Codes: G06K 7/10603 Basic scanning using moving elements
• CPC Class Codes: G06K 7/10663 using hologram
• CPC Class Codes: G06K 7/10673 Parallel lines
• CPC Class Codes: G06K 7/10693 for omnidirectional scanning
• CPC Class Codes: G06K 7/10702 Particularities of propagating elements, e.g. lenses, mirrors G06K7/10831 takes precedence
• CPC Class Codes: G06K 7/10792 Special measures in relation to the object to be scanned
• CPC Class Codes: G06K 7/10801 Multidistance reading
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/10851 : Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03
• CPC Class Codes: G06K 7/10861 : sensing of data fields affixed to objects or articles, e.g. coded labels postal sorting B07C3/14, conveying articles B65G47/48
• CPC Class Codes: G06K 7/10871 : randomly oriented data-fields, code-marks therefore, e.g. concentric circles-code
• CPC Class Codes: G06K 7/10881 : constructional details of hand-held scanners
• CPC Class Codes: G06K 7/10891 : the scanner to be worn on a finger or on a wrist
• CPC Class Codes: G06K 7/109 : adaptations to make the hand-held scanner useable as a fixed scanner
• CPC Class Codes: G06K 7/14 : using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G07F 9/002 : Vending machines being part of a centrally controlled network of vending machines
• CPC Class Codes: G07G 1/0045 : with a code reader for reading of an identifying code of the article to be registered, e.g. barcode reader or radio-frequency identity [RFID] reader
• CPC Class Codes: G07G 1/0054 : with control of supplementary check-parameters, e.g. weight or number of articles

Abstract

A bar code symbol scanning system having a holographic laser scanning disc utilizing maximum light collection surface area thereof and having scanning facets with optimized light collection efficiency. The holographic scanning disc has a plurality of holographic optical elements for scanning a laser beam and producing a laser scanning pattern for scanning code symbols. Each holographic optical element being supported on a support disc between the inner and outer perimeters thereof, and each has a surface area for carrying out light collecting operations and at least a portion of the surface area is disposed adjacent the outer perimeter of the support disc for carrying out laser beam scanning operations. The sum of all of the facet surface areas of the plurality of said holographic optical elements is substantially equal to the surface area of the available light collecting region of the support disc.

Claims

1. A bar code symbol scanning system for producing a laser scanning pattern having a plurality of scanlines over a plurality of different focal planes within a 3-D scanning volume for scanning bar code symbols presented within said 3-D scanning volume, said bar code symbol reading system comprising:

a housing;

a support disc disposed within said housing, being rotatable about an axis of rotation, and having an inner perimeter, an outer perimeter, and an available light collecting region defined between said inner perimeter and outer perimeter;

a plurality of holographic optical elements for scanning a laser beam and producing a laser scanning pattern having a plurality of scanlines over a plurality of different focal planes within a 3-D scanning volume for scanning bar code symbols presented within said 3-D scanning volume, each said holographic optical element being supported on said support disc between the inner and outer perimeters, and each said holographic optical element having a surface area for carrying out light collecting operations, and at least a portion of said surface area being disposed adjacent said outer perimeter of said support disc for carrying out laser beam scanning operations;

a light focusing mirror disposed beneath said support disc, for focusing light rays collected by each said holographic optical element; and

a photodetector disposed above said support disc, for detecting the intensity of light rays collected by each said holographic optical element, focused by said light focusing mirror, and transmitted through said holographic optical element onto said photodetector for detection and generation of an electrical signal indicative of said detected intensity;

wherein the sum of all of the surface areas of said plurality of holographic optical elements is substantially equal to the surface area of said available light collecting region of said support disc; and

wherein the amount of light collected by each said holographic optical element and focused onto said photodetector by said light focusing mirror is substantially equal during said light collecting operations.

2. The bar code symbol scanning system of claim 1, wherein the refractive index of each said holographic optical element has a variable spatial frequency over its surface area, providing a focal length which is related to the distance of the scanline to be produced by said holographic optical element.

3. The bar code symbol scanning system of claim 1, wherein the light collection efficiency of each said holographic optical element is substantially equal.

4. The bar code symbol scanning system of claim 1, wherein the inner surface boundary of at least one of said holographic optical elements has an inner radius which is substantially greater than the inner perimeter of said support disc.

5. The bar code symbol scanning system of claim 1, wherein each said holographic optical element is a volume transmission type hologram.

6. The bar code symbol scanning system of claim 1, wherein each said holographic optical element is a volume reflection type hologram.

7. The bar code symbol scanning system of claim 1, wherein the average refractive index of each said holographic optical element is substantially equal over the entire surface area thereof.

8. The bar code symbol scanning system of claim 1, wherein the outer portion of the surface area of each said holographic optical element used for scanning operations has a first average refractive index, whereas the remaining portion of the surface area of each said holographic optical element used for light collecting operations has a second average refractive index.

9. The bar code symbol scanning system of claim 8, wherein said first average refractive index is different from said second average refractive index.

10. The bar code symbol scanning system of claim 1, wherein the light diffraction efficiency of said outer portion of said surface area is optimized for a first polarization state of light, and the light diffraction efficiency of said remaining portion of said surface area is optimized for a second polarization state of light orthogonal to said first polarization state.

11. The bar code symbol scanning system of claim 10, wherein said first polarization state is the S polarization state, and said second polarization state is the P polarization state.

12. A holographic laser scanning system for scanning code symbols, comprising:

a housing;

laser beam producing means for producing a laser beam; and

a laser scanning disc disposed within said housing, having a total surface area available for light collection, and plurality of holographic optical elements for scanning said laser beam and producing a laser scanning pattern for scanning code symbols,

wherein each said holographic optical element has an optimized light collection efficiency and a light collection surface area which is maximized with respect to said total surface area available for light collection.

13. A holographic laser scanner comprising:

laser beam producing means for producing a laser beam;

a support disc rotatable about an axis of rotation, and having an inner perimeter, an outer perimeter, and an available light collecting region defined between said inner perimeter and outer perimeter; and

a plurality of holographic optical elements for scanning said laser beam and producing a laser scanning pattern for scanning code symbols, each said holographic optical element being supported on said support disc between the inner and outer perimeters of said support disc, and each having a surface area for use in light collecting operations,

wherein substantially all of the available light collecting surface area on said support disc is utilized and the light collection efficiency of each said holographic optical element is substantially equal.

14. A holographic laser scanner for scanning code symbols, comprising:

a laser for producing an outgoing laser beam;

a support disc having an axis of rotation, and an inner perimeter, an outer perimeter, and an available light collecting region defined between said inner perimeter and said outer perimeter; and

a plurality of holographic optical elements for scanning said laser beam and producing a laser scanning pattern for scanning code symbols, each said holographic optical element being supported on said support disc between the inner and outer perimeters of said support disc, and each having a light collection area for use in light collecting operations,

wherein the size and shape of the light collection area of each holographic optical element is controlled independent of the angular sweep of said outgoing laser beam in order to make maximum use of the disk surface area for light collection functions during laser scanning operations.